We've had a few cats. The one just before our last cat got renal failure (pretty common I guess). The vet gave us a choice of putting the cat down or administering drips under his skin. We extended him maybe a year(?). He would do really good after a drip then start to taper off. Eventually they got to where they weren't working and he sadly left us. Wife wants another cat but we can't risk it with all the snacks flying around.
A cat, dog or a parrot can get under your skin and be a big part of your life.
When they are gone there is a big empty spot that you can`t fill.
Sorry for your loss.
Ray